CN107209113A - Spectral device and method - Google Patents
Spectral device and method Download PDFInfo
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- CN107209113A CN107209113A CN201580075183.6A CN201580075183A CN107209113A CN 107209113 A CN107209113 A CN 107209113A CN 201580075183 A CN201580075183 A CN 201580075183A CN 107209113 A CN107209113 A CN 107209113A
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/28—Investigating the spectrum
- G01J3/40—Measuring the intensity of spectral lines by determining density of a photograph of the spectrum; Spectrography
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/28—Investigating the spectrum
- G01J3/42—Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry
- G01J3/433—Modulation spectrometry; Derivative spectrometry
- G01J3/4338—Frequency modulated spectrometry
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
- G01N21/03—Cuvette constructions
- G01N21/031—Multipass arrangements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
- G01N2021/396—Type of laser source
- G01N2021/399—Diode laser
Abstract
Describe a kind of device (2) for being used to measure the amount of the analyte in mixture.In one example, device (2) has the lasing light emitter (6) for being used for generating laser of frequency modulation beam (22).Chamber (36) receives laser of frequency modulation beam (22), and photoelectric detector (46) obtains the strength signal for the interaction for indicating laser of frequency modulation beam (22) between mixture.Device (2) has the first demodulator (76) for being used for producing the first demodulated signal.The carrier frequency of laser of frequency modulation beam (22) and the pattern of chamber (36) are locked to each other by Frequency Locking mechanism using the first demodulated signal.Device has the second demodulator (50) for being used to produce the second demodulated signal and the output for the amount that generates the analyte in indicating mixture based on the second demodulated signal.Also describe other apparatus and method.
Description
Technical field
The present invention relates to spectral device and method.
Background technology
Spectral device and method for the amount that measures the analyte in mixture are known.
In known spectrographic technique, absorption of the analyte to the light of some characteristic wavelengths can be used to find out mixture
In analyte amount.In known spectrographic technique, the laser with initial strength is and saturating by mixture by mixture
The intensity for the light crossed is measured.This allows the Absorption Characteristics for obtaining mixture, and determines therefrom that analyte in mixture
Amount.
Generally speaking, expect to provide following spectral device and method：The spectral device and method provide high s/n ratio and
With simplified and/or more effective processing.
The content of the invention
, should according to the first aspect of the invention there is provided a kind of device for being used to measure the amount of the analyte in mixture
Device includes：
Lasing light emitter, the laser of frequency modulation beam being frequency-modulated for generating under modulating frequency；
Chamber, is arranged to receive laser of frequency modulation beam；
Photoelectric detector, the strength signal of the interaction between laser of frequency modulation beam and mixture is indicated for obtaining；
First demodulator, for producing the first demodulated signal by being demodulated to strength signal；
Frequency Locking mechanism, is arranged to using the first demodulated signal come by the mould of the carrier frequency of laser of frequency modulation beam and chamber
Formula is locked to each other；And
Second demodulator, for producing the second demodulated signal by being demodulated to strength signal, and for based on
Second demodulated signal generates the output of the amount of the analyte in indicating mixture.
The first demodulated signal is produced by being demodulated to same strength signal and the second demodulated signal makes it possible to
Transmission, laser off resonance and laser bandwidth of the laser beam by mixture are controlled and handled with single modulated signal.Therefore, to light
The processing and control of the example of spectral apparatus can be than being configured as (for example, using more than one modulator) under multiple modulating frequencies
The known spectral device of modulating lasering beam is more direct.
In this example, the device includes the chamber for being arranged to receive laser of frequency modulation beam.The use of chamber makes laser of frequency modulation beam
Path length increase, this improves sensitivity of the measurement to the amount of the analyte in mixture.For example, making laser of frequency modulation beam
Carrier frequency and the pattern of chamber, which are locked to each other, can minimize the wave length shift and line width of laser beam, and this can be improved in this example
Measurement sensitivity.
In this example, strength signal is demodulated in a frequency domain and in non-temporal and avoids laser from switching and strength signal
The synchronous noise transient of demodulation and do not have the contributive dark cycle to the final output of the amount of the analyte in indicating mixture
(dark period)。
Mixture can be single analyte for example in single " background " material or " matrix " material or in background material
Single analyte in the mixture of material or the multiple analytes in uniform background material or the mixture in background material
In multiple analytes.Background material can be for example one or more gases.
In one embodiment, the first demodulator be arranged to by being demodulated under modulating frequency to strength signal and
Produce the first demodulated signal.In one embodiment, the second demodulator is arranged to by under the multiple frequency of modulating frequency
Strength signal is demodulated to produce the second demodulated signal.The multiple of modulating frequency both can be the non-integral multiple of modulating frequency
Or integral multiple (i.e. harmonic wave).For example, the second demodulator can be arranged to by under twice of modulating frequency to strength signal
It is demodulated to produce the second demodulated signal.As explained above, same strength signal is demodulated to produce the first solution
Both signal and the second demodulated signal is adjusted to allow device quilt simpler than known devices and cheaper than known devices in this example
Use.
In one embodiment, Frequency Locking mechanism is arranged to that the carrier frequency of laser of frequency modulation beam is adjusted to and expected
Chamber pattern correspondence.Alternatively, or in addition, Frequency Locking mechanism can be arranged to be and frequency modulation by the mode adjustment of chamber
The expectation carrier frequency correspondence of laser beam.
In one embodiment, Frequency Locking mechanism is arranged to the carrier frequency and (ii) of (i) laser of frequency modulation beam
At least one in the pattern of chamber is locked to the chamber pattern with the immediate frequency of radiation transistion frequency of analyte.
In one embodiment, Frequency Locking mechanism includes being used to change the device of the length of chamber.This in this example can be with
It is used to change cavity length, the carrier frequency of the pattern of chamber and laser of frequency modulation beam is locked to each other.
In one embodiment, chamber is that each chamber in one of multiple chambers, the plurality of chamber is used to receive laser of frequency modulation beam.
In example, multiple chambers can be used to respond the analyte concentration of different stage.
In one embodiment, spectral device includes micro-resonator.In this example, mean can be with for the use of micro-resonator
Produce the cost compared with known device with the size reduced and/or reduction and generally more sane spectral device.Example
Such as, micro-resonator can be micro-ring resonator.
In one embodiment, during micro-resonator is a micro-resonator in multiple micro-resonators, these micro-resonators
Each micro-resonator be used to increase the intensity of laser of frequency modulation beam.It can alleviate saturation using such multiple micro-resonators to imitate
Should.
In one embodiment, photoelectric detector is arranged to the strength signal indicating mixture obtained and by laser of frequency modulation
Interaction between the evanescent field that beam is produced beyond chamber.For example, when the laser of frequency modulation beam of intracavitary incide the inside of chamber with
When on the border between external environment condition, evanescent field can be produced.Evanescent field is incided on mixture and with mixing in this example
Thing interacts, and the mixture is in such an example beyond chamber.
In various embodiments, chamber can be used for accommodating mixture in use.The chamber of the embodiment can be by example
As Fabry-Perot etalon (Fabry-Perot etalon) is provided.In such embodiments, photoelectric detector is arranged
The intensity of laser of frequency modulation beam by mixture can be indicated for the strength signal of acquisition.
Such as from above, clearly, many different chamber types are adapted to use in spectral device, so as to enter for user
Luggage puts customization and provides abundant design freedom.
In one embodiment, the analyte in the output indication mixture of the amount of the analyte in indicating mixture is dense
Degree.For example, output can indicate the ratio of the analyte compared with one or more other components of mixture.
Another embodiment, which is related to, includes the hygrometer of the device according to examples described above.Hygrometer can be used to
The amount of the water in mixture is measured, for example, the amount of the water in surrounding environment or specific mixture sample.
There is provided a kind of spectrum side for being used to measure the amount of the analyte in mixture according to the second aspect of the invention
Method, this method includes：
Generate the laser of frequency modulation beam being frequency-modulated under modulating frequency；
Laser of frequency modulation beam is delivered in chamber；
Obtain the strength signal for indicating the interaction between laser of frequency modulation beam and mixture；
The first demodulated signal is produced by being demodulated to strength signal；
The pattern of the carrier frequency of laser of frequency modulation beam and chamber is locked to each other using the first demodulated signal；
The second demodulated signal is produced by being demodulated to strength signal；And
The output of the amount of analyte in indicating mixture is generated based on the second demodulated signal.
In one embodiment, the first demodulated signal of generation is included under modulating frequency is demodulated to strength signal.
In a kind of embodiment, produce the second demodulated signal and be included in the multiple frequency of modulating frequency (for example, two frequencys multiplication of modulating frequency
Rate) under strength signal is demodulated.
In one embodiment, the pattern of the carrier frequency of laser of frequency modulation beam and chamber is locked to each other including by laser of frequency modulation
The carrier frequency of beam is adjusted to corresponding with desired chamber pattern.In one embodiment, by the carrier frequency of laser of frequency modulation beam and
The pattern of chamber, which is locked to each other, can alternatively, or in addition include carrying the mode adjustment of chamber for the expectation with laser of frequency modulation beam
Wave frequency rate correspondence.
In one embodiment, laser of frequency modulation beam is delivered into chamber includes laser of frequency modulation beam being delivered to and mixture neighbour
In near chamber, the intensity letter that strength signal includes obtaining the interaction between the evanescent field beyond indicating mixture and chamber is obtained
Number, evanescent field is produced by the interaction of laser of frequency modulation beam and chamber.
In a kind of different embodiment, laser of frequency modulation beam is delivered into chamber includes making laser of frequency modulation beam mixed by accommodating
The chamber of compound, obtains the strength signal that strength signal includes obtaining the intensity for indicating laser of frequency modulation beam by mixture.
In one embodiment, the pattern of the carrier frequency of laser of frequency modulation beam and chamber is locked to each other with being solved based on second
Adjust signal and performed come the output for the amount for generating the analyte in the indicating mixture substantially the same time.With for example measuring institute
The known method that laser beam is locked into specific carrier frequency before or after the amount of the analyte of presence is compared, and this is provided more
Efficient control.
In one embodiment, the pattern of the carrier frequency of laser of frequency modulation beam and chamber is locked to each other including by (i) frequency modulation
At least one in the carrier frequency of laser beam and the pattern of (ii) chamber is locked to the radiation transistion frequency with analyte
The chamber pattern of immediate frequency.In a kind of alternate embodiments, by the carrier frequency of laser of frequency modulation beam and the pattern of chamber that
This locking include will at least one in the carrier frequency of (i) laser of frequency modulation beam and the pattern of (ii) chamber be locked to have except with
The pattern of the chamber of frequency outside the immediate frequency of frequency of the radiation transistion of analyte.
In one embodiment, spectrographic technique includes：
By the Carrier frequency lock of laser of frequency modulation beam to when laser of frequency modulation beam is by mixture, laser of frequency modulation beam is substantially
There is no the frequency that analyte absorbs；
Laser of frequency modulation beam is delivered in chamber；
Obtain the second strength signal for indicating the interaction between laser of frequency modulation beam and mixture；
The 3rd demodulated signal is produced by being demodulated to the second strength signal；And
Generated based on the 3rd demodulated signal and indicate that one or more components in mixture in addition to analyte are inhaled
The output of the amount of the laser of frequency modulation beam of receipts.
Using obtained by the embodiment, indicate that one or more components in addition to analyte absorb in mixture
The output of amount of laser of frequency modulation beam can be used for calibration purpose.
In one embodiment, the 3rd demodulated signal by under the multiple frequency of modulating frequency (for example, in modulating frequency
Doubled frequency under) strength signal is demodulated to produce.
In one embodiment, the analyte in the output indication mixture of the amount of the analyte in indicating mixture is dense
Degree.For example, the output can indicate the ratio of the analyte compared with one or more other components of mixture.
In one embodiment, mixture includes at least one gas.Analyte can be in itself gas, for example, with water
The water of vaporous form.Therefore, spectrographic technique can be used to for example determine in gas or admixture of gas (including such as air)
In vapor amount.
In one embodiment, analyte includes one or more in following item：Oxygen, hydrogen fluoride or sulfur dioxide.
In another embodiment, the component in mixture in addition to analyte includes one or more in following item：Air, first
Alkane, hydrogen, carbon dioxide or sulfur hexafluoride.For example, the component in mixture in addition to analyte can be one or more
" matrix " material or background material.
In one embodiment, laser of frequency modulation beam is frequency-modulated under multiple modulating frequencies, the plurality of modulating frequency bag
Include the modulating frequency.In this embodiment, quilt under each modulating frequency that strength signal can be in the plurality of modulating frequency
Demodulation.Alternately, strength signal can be demodulated under the frequency in addition to the plurality of modulating frequency.In a kind of embodiment
In, laser of frequency modulation Shu Liyong pseudorandom modulation signals are frequency-modulated.
In one embodiment, spectrographic technique is included by being solved under one or more of the other frequency to strength signal
Transfer to produce one or more of the other demodulated signal.In this embodiment, one or more of the other frequency can each exceed
Twice of the modulating frequency.
, should according to the third aspect of the invention we there is provided a kind of device for being used to measure the amount of the analyte in mixture
Device includes：
Lasing light emitter, the laser of frequency modulation beam being frequency-modulated for generating under modulating frequency；
Photoelectric detector, the strength signal for obtaining the intensity for indicating laser of frequency modulation beam by mixture；
First demodulator, for producing the first demodulated signal by being demodulated to strength signal；
Frequency Locking mechanism, be arranged to using the first demodulated signal come by the carrier frequency of laser of frequency modulation beam and expect frequency
Rate is locked to each other；And
Second demodulator, for producing the second demodulated signal by being demodulated to strength signal and for based on
Two demodulated signals generate the output of the amount of the analyte in indicating mixture.
There is provided a kind of spectrum side for being used to measure the amount of the analyte in mixture according to the fourth aspect of the invention
Method, this method includes：
Generate the laser of frequency modulation beam being frequency-modulated under modulating frequency；
Laser of frequency modulation beam is delivered in mixture；
Obtain the strength signal for the intensity for indicating laser of frequency modulation beam by mixture；
The first demodulated signal is produced by being demodulated to strength signal；
The carrier frequency and expected frequency of laser of frequency modulation beam are locked to each other using the first demodulated signal；
The second demodulated signal is produced by being demodulated to strength signal；And
The output of the amount of analyte in indicating mixture is generated based on the second demodulated signal.
In these aspects, with previous aspect on the contrary, not providing chamber for laser of frequency modulation beam.Alternatively, it can use
Other mechanisms.
In the following description to the preferred embodiments of the present invention carried out from refer to the attached drawing, further feature of the invention and excellent
Point be will be apparent, and these preferred embodiments are only presented as example.
Brief description of the drawings
Fig. 1 schematically shows the exemplary spectroscopy of laser of frequency modulation beam；
Fig. 2 schematically shows the amount for being used to measure the analyte in mixture according to an embodiment of the present
Spectral device example；
Fig. 3 schematically shows the illustrated examples of the operating principle of example Fabry-Perot etalon；
Fig. 4 schematically shows the dress of the exemplary spectroscopy including multiple micro-resonators according to an embodiment of the present
Put；And
Fig. 5 is schematically shown according to another embodiment of the invention for measuring the analyte in mixture
The example of the spectral device of amount.
Embodiment
According in a kind of spectrographic technique of example, laser of frequency modulation beam is passed in chamber.Strength signal is used to swash
The carrier frequency of light and the pattern of chamber are locked to each other, and also provide for the measurement of the amount to the analyte in mixture.
In example, the use of chamber improves property compact to design, because it allows in the case of the physical size of aggrandizement apparatus to prolong
The long optical path length by analyte.In addition, the spectral device with chamber can also be high precision, sane and low cost
, especially in the case where chamber is so-called " microcavity ".For example, can be carried using the spectral device of the chamber with high-fineness
Reduced for signal enhancing and 1/f noise.(fineness (finesse) of optical resonator or chamber can be defined as its freedom
Spectral region divided by its resonant bandwidth (full width at half maximum (FWHM)).)
It can be used together according to the spectral device of embodiment with a variety of chambers, these chambers include but is not limited to linearly
The chamber (such as Fabry-Perot etalon) of type and the waveguide microcavity that can be built on sub-millimeter scale, i.e., micro- resonance
Device.For that can be hollow or other forms with the chamber that the device is used together, and mixture can be accommodated or can be with
Mixture is not accommodated, as discussed further below.
In one example, using single modulating frequency；In other examples, more than one modulating frequency can be used.
In this example, the carrier frequency of laser beam is locked into corresponding with the centre frequency of the Absorption Characteristics of analyte interested
Chamber pattern.However, in other examples, carrier frequency can be locked into other chamber patterns.In other embodiments, can example
Such as by changing cavity length to adjust carrier frequency and chamber pattern corresponding pattern lock by chamber of the pattern until laser beam of chamber
Surely the carrier frequency of laser beam is arrived.
In this example, in modulating frequency ωmUnder beat sound (beat note) (also referred to as 1f) be used to lock
The carrier frequency of laser beam.In one example, it is known that Pound-Drever-Hall technologies can be used for carrier frequency
This locking, but alternative lock-in techniques can also be used.In twice of the ω of modulating frequency 2mIt is lower and with output field phase
The beat sound (also referred to as 2f orthogonal terms) of position 1/4 wavelength of difference has the amplitude proportional to analyte concentration.Therefore, measure
2f allow the amount of the analyte in determination mixture.In other examples, strength signal can be demodulated under other frequencies,
The pattern of carrier frequency and chamber is locked to each other and/or provided the output for the amount for indicating analyte.
In more detail, in Fig. 1 exemplary spectroscopy method, laser of frequency modulation beam performs laser two by using signal generator
The active frequency of pole pipe is modulated and generated.In other examples, laser beam can be firstly generated, and then for example using acousto-optic
Modulator or electrooptic modulator to carry out frequency modulation(PFM) to the laser beam.It is, for example, possible to use all-fiber electro-optical modulator is come pair
Laser beam carries out frequency modulation(PFM).The frequency modulation(PFM) of laser beam enables laser frequency and therefore optical maser wavelength is stablized, simultaneously
Also repel low-frequency noise.
The electric field generated before frequency modulation(PFM) by laser beam can be represented by the real part of following formula：
E (x, t)=E0ei(ωt-kx)
Wherein E (x, t) is electric field of the t at the x of position, E0It is the amplitude of electric field, i is imaginary unit, and ω is laser
Frequency, and kx is phase angle.
In modulating frequency ωmThe electricity that frequency modulation(PFM) produces following form is carried out to laser Injection Current by sinusoidal manner down
：
Wherein M sin (ωmT+ ψ) item is amplitude modulation(PAM), and the instantaneous phase of electric field is (ωmt+βsin(ωmt))。
After Jacobi-Anger identities have been used, the equation can be rewritten as：
Wherein Jn(β) is first kind n rank Bessel functions.The equation shows that the Fourier transformation for the electric field modulated will be wrapped
Containing an infinite number of frequency component, these frequency components are in this case sideband to (sideband pair).
In this example, exponent number | n |>1 component is inessential, so that the equation be reduced to：
Wherein β is modulation amplitude.
Fig. 1 schematically shows the example of the spectrum of the Fourier transformation of above-mentioned laser beam, and Fig. 1 shows carrier frequency
ωcAnd in ωc+ωmAnd ωc-ωmTwo single order sidebands at place.Existing in the path of laser of frequency modulation beam includes absorbability
(absorbing) mixture of analyte causes the introducing of transfer function：
Wherein δnIt is amplitude fading, and φnIt is in angular frequency by analytec+nωmThe phase shift of lower initiation.
Transfer function is incorporated into the expression formula of the electric field of laser of frequency modulation beam and intensity is obtained to electric field is squared,
Thus obtain：
Wherein I (t) is the intensity of laser of frequency modulation beam by mixture, and wherein * instructions take the complex conjugate of item.
In β<<1 and for simplicity omit in amplitude modulation(PAM) M example, the item of higher-order can be omitted with
Obtain：
Last six of the equation are included in modulating frequency ωmUnder sine term and in twice of ω of modulating frequency 2mUnder
The summation of sine term.These can be extracted by a series of mixing and filtering.As the skilled person will appreciate
And as described in greater detail below, this can use such as phase sensitive detector to realize.
After certain operations, the item under modulating frequency and the item under twice of modulating frequency can be represented as：
WhereinAnd Re and Im refer respectively to real and imaginary parts.
If including additional amplitude modulation(PAM) M, and if β, M ＜ ＜ 1, then the electric field of laser of frequency modulation beam is given by following formula
Go out：
The formula corresponds to the intensity of following formula：
Wherein I0Comprising the item for representing detector efficiency, and：
Obtained using Euler's identity：
Assuming that | δ0-δ±1| ＜ ＜ 1 and | φ0-φ±1| ＜ ＜ 1 are to cause ex≈ 1+x, then ωmWith 2 ωmThe amplitude of item can
To be write out according to δ and φ, to provide：
The strength signal can be demodulated under modulating frequency with produce the first demodulated signal (this can be referred to as " 1f examine
Survey ").The strength signal can also be demodulated under twice of modulating frequency, and to produce the second demodulated signal, (this can be referred to as
" 2f detections ").In other examples, strength signal can be demodulated under other frequencies with produce the first demodulated signal and/or
Second demodulated signal.For example, strength signal can be demodulated under the multiple of modulating frequency, the multiple can be integral multiple or non-
Integral multiple.Alternately, strength signal can some frequencies and/or difference (for example, some multiples of modulating frequency) under quilt
Demodulation.
Fig. 2 shows the signal for being used to measure the exemplary spectroscopy device 2 of the amount of the analyte in mixture according to embodiment
Property diagram.Voltage controlled oscillator 4 is used to modulation and is supplied to the electric current of laser diode 6 via electrical connection 8, but shows other
The electric current can be modulated by other devices (such as, function generator) in example.In this example, Injection Current is about 100,000
Modulated under the frequency of hertz (kHz), but depending on the application-specific of such as this method and device, other modulation can be used
Frequency.
Measurement to the small change of the absorption signal on big background signal needs to carefully select the feature to be detected
Absorption frequency, adding (coupled with) sets the maximized machinery of signal intensity.Voltage controlled oscillator 4 is to laser diode
6 electric currents of the supply with modulating frequency, the modulating frequency is selected for generating the laser of frequency modulation beam with desired carrier frequency.
For example, the carrier frequency of laser of frequency modulation beam there can be the magnitude of hundreds of Terahertzs (THz), but supplied by voltage controlled oscillator 4
Electric current can be modulated under the frequency with hundreds of kHz magnitudes.In this example, the carrier frequency of laser of frequency modulation beam is with treating
The radiation transistion correspondence of the analyte of detection.In the case where minor amount of water is detected, such as assemblage zone can be used from base vibrational state
To the relatively strong transition of the first excited vibrational state, the transition is represented with spectral cue (1,0,1) ← (0,0,0).
In Mulliken marks, this is A1→B2The transition of type.
The laser diode that laser diode 6 encapsulates for butterfly in this example, but can alternatively use other classes
The laser diode of type or the laser even in addition to laser diode.
Tuning (tuning) device 10 is used to control the coarse adjustment and fine setting of Injection Current.In the figure 2 example, tuning dress
Putting 10 includes laser current driver 14, and laser current driver 14 is biased to drive sharp via the offer direct current of electrical connection 16 (DC)
Optical diode 6.Voltage controlled oscillator 4 provides exchange (AC) signal under modulating frequency via electrical connection 8.In this example, adjust
Humorous device 10 also includes the temperature control 18 being connected via electrical connection 20 with laser diode 6.In other examples, it can not deposit
It can include the component different from Fig. 2 tuner 10 in the tuner for adjusting Injection Current, or tuner.
In the figure 2 example, the laser of frequency modulation beam 22 generated by laser diode 6 incides optical facilities (optical
Arrangement on).Optical facilities can be used for such as phase of adjustment laser of frequency modulation beam 22, polarization
And/or (beam waist) diameter with a tight waist (polarisation).In other examples, laser of frequency modulation beam does not pass through optics machine
Structure, but directly pass through mixture.
In fig. 2, optical facilities include half-wave plate 24, the first polarization beam apparatus 26, the mirror of the first mirror (mirror) 28, second
30th, the second polarization beam apparatus 32 and quarter wave plate 34.Optical facilities guiding laser of frequency modulation beam 22, so that laser beam 22 incides chamber
36。
The chamber 36 of Fig. 2 exemplary spectroscopy device 2 is confocal cavity.First lens 38 and the second lens 40 are disposed in chamber 36
Either side.First lens and the second lens 38,40 are configured such that the focus of incident beam is located at the center of chamber 36.Chamber 36 is also
The first mirror 42 and the second mirror 44 including the opposite sides positioned at chamber 36, wherein the first mirror 42 be disposed in chamber 36 with it is first saturating
The identical side of mirror 38, the second mirror 44 be disposed in chamber 36 with the identical side of the second lens 40.In the figure 2 example,
One mirror and the second mirror 42,44 have the corresponding song of the radius of curvature of the field with inciding the laser of frequency modulation beam 22 on the first lens 38
Rate radius.In other examples, chamber can be asymmetrical, and wherein mirror has corresponding curvature half not with the radius of curvature of field
Footpath, with cause laser of frequency modulation beam 22 it is with a tight waist not chamber midpoint.It is more fully described below with reference to Fig. 3 in spectrum dress
Put the example chamber used in 2.
The sample of mixture can enter chamber 36 via sample inlet 43 and leave chamber 36 via sample export 45.Cause
This, in the figure 2 example, mixture is accommodated in intracavitary.However, in the other examples of spectral device, such as with reality
The chambers of the heart and hereinafter by spectral device discussed in detail, mixture can not be in intracavitary.Mixture can be substituted
Ground and chamber near or adjacent to, for example, so that mixture incide on the surface of the surface of chamber or the container of chamber or with chamber
The surface contact of the container of surface or chamber.(here, the use on " solid chamber ", it should be borne in mind that chamber is sharp for accommodating
Light beam 22, and therefore chamber can be " solid " for mixture, but it is (translucent) of printing opacity, or
It is " chamber " for laser beam 22.)
Fig. 2 laser of frequency modulation beam 22 enters chamber 36 by the first lens 36 and the first mirror 42.Laser of frequency modulation beam 22 is then logical
Cross the mixture being contained in chamber 36.At least a portion of laser of frequency modulation beam 22 leaves chamber by the second mirror 44 and the second lens 40
36, and incide on the first photoelectric detector 46.The different parts of laser of frequency modulation beam 22 can be reflected by the second mirror 44, and
And be retained in intracavitary or leave chamber by the first mirror 42 and the first lens 38, below with reference to described by Fig. 3.
The incident portion of laser of frequency modulation beam 22 is converted into strength signal by the first photoelectric detector 46, and the strength signal is indicated
Interaction between laser of frequency modulation beam 22 and mixture.In this example, strength signal indicates tune by mixture
The intensity of frequency laser beam 22；In other examples, strength signal can indicate the difference between laser of frequency modulation beam 22 and mixture
Interaction.In the figure 2 example, strength signal is the electronics that the first phase sensitive detector 50 is sent to via electrical connection 48
Signal, the first phase sensitive detector 50 receives the input reference voltage for carrying out voltage controlled oscillator 4 via electrical connection 52.First phase sensitivity is examined
Survey device 50 to be in this example demodulated strength signal under twice of modulating frequency, to produce the second demodulated signal, and base
The output of the amount of analyte in indicating mixture is generated in the second demodulated signal.As explained above, in other examples
In, strength signal can be demodulated under different frequencies (for example, other integral multiples or non-integral multiple of modulating frequency), to obtain
Obtain the second demodulated signal.Phase-sensitive detection in exemplary spectroscopy device is more fully hereinafter described.
In this example, analyte is vapor, and mixture is the mixture of air and vapor.Therefore, at this
The amount for the vapor that the output indication obtained in example is present, i.e. the humidity in chamber 36.In the example of measurement humidity, water leads to
It is considered as often various industrial process gas, the work especially used in semiconductor and solid-state illumination manufacture, battery production etc.
Industry process gas, in pollutant.In these cases, there is cost less than the micro-analysis thing of parts per billion to concentration
The measurement of benefit is desired.For example, in the case of water, matrix gas is drier, obtained in various manufacturing processes
The yield and performance of product are higher.This means for example faster microprocessor can be produced with higher yield, it is brighter
Bright LED and more efficient battery.Other industrial process (control for including such as fuel cell) are needed to high concentration (example
Such as, close to saturation) humidity accurate measurement.In a word, the improved control energy in many industry and manufacture application to humidity
Enough bring the efficiency of raising.
It will be appreciated by those skilled in the art that spectrographic technique may be utilized for measuring other analyses in other mixtures
Thing.For example, spectrographic technique can be used to measure the methane in air or the ammonia in the release gas of bioreactor.
In other examples, spectrographic technique can be used to detect the compound of some diseases of instruction in the gas of people's exhalation.For example,
There is the symptom that nitric oxide (NO) is probably asthma in the gas that people breathes out, and there is formaldehyde in the gas that people breathes out can
Breast cancer can be imply.
In other examples, analyte includes one or more in following item：Oxygen, hydrogen fluoride or sulfur dioxide.
In example, component in mixture in addition to analyte (such as one or more " matrix " components or background component) include with
One or more in lower gas：Air, methane, hydrogen, carbon dioxide or sulfur hexafluoride.
In this example, spectrographic technique can be used to monitoring and be used as insulant, gas isolated high pressure using sulfur hexafluoride
The humidity of environment around switchgear (switchgear).If sulfur hexafluoride is contacted with water, it can react with
Formation can corrode the hydrogen fluoride, sulfur dioxide and sulfuric acid of switchgear.Therefore, in this example, using spectrographic technique to environment
Humidity is monitored and reduction humidity can be used to reduce the corrosion of switchgear when necessary.
Fig. 2 example is gone to, the output of the first phase sensitive detector 50 in this example is sent to via electrical connection 54
Front console 56, front console 56 provides the output of the amount of the analyte in indicating mixture via digital reading 58.Front end face
Plate 56 also includes the front controller 60 that tuner 10 is connected to via electrical connection 62, and front controller 60 can be used to set
Put the various parameters of spectral device 2.For example, front controller 60 can be used to modulate or control to be supplied to by tuner 10
The electric current of laser diode 6.In other examples, the output of the first phase sensitive detector 50 can be used by different way, example
Such as it is used as the input of other electronic building bricks.
In the figure 2 example, PZT (piezoelectric transducer) 64 provides the length to chamber 36 via the mechanical connection 66 with the second mirror 44
Mechanical fine adjustment.The need for this is eliminated to the length of accurate control chamber 36 during manufacture.Tune is locked into the pattern of chamber
In the other examples of the carrier frequency of frequency laser beam, the length of chamber 36 can be scanned some microns, and some microns for example may be used
With the magnitude with some Free Spectral Ranges, as described further below.
As explained above, at least a portion of laser of frequency modulation beam 22 can be between the first mirror and the second mirror 42,44
The one or many reflections of experience.A part for laser of frequency modulation beam 22 leaves chamber by the second mirror 44 and the second lens 40, and enters
It is mapped on the first photoelectric detector 46, as described earlier.Another part of laser of frequency modulation beam 22 is from the second mirror 44 towards
One mirror 42 reflects, and leaves chamber 36 by the first mirror 42 and the first lens 38.
The part 68 that the optical facilities described before of laser of frequency modulation beam are reflected back incide on quarter wave plate 34 and
It is then incident on the second polarization beam apparatus 32.Second polarization beam apparatus 32 is by the part 68 of laser of frequency modulation beam and incident tune
Frequency laser beam 22 is separated, and the part 68 of laser of frequency modulation beam is guided to the 3rd mirror 70, the 3rd mirror 70 reflection laser of frequency modulation
The part 68 of beam is so that it is incided on the second photoelectric detector 72.
The part 68 of laser of frequency modulation beam is converted into indicating the part 68 of laser of frequency modulation beam by the second photoelectric detector 72
Intensity electric strength signal.The strength signal is sent to the second phase sensitive detector 76 via electrical connection 74.Second phase sensitivity is examined
Survey device 76 similarly to operate with the first phase sensitive detector 50, and be also connected to voltage controlled oscillator 4 via electrically connecting 78, but the
Two phase sensitive detectors 76 are configured as producing the first demodulated signal by being demodulated strength signal under modulating frequency.
In other examples, the second phase sensitive detector 76 is configured as in the frequency in addition to modulating frequency (for example, times of modulating frequency
Number or two frequencies and/or difference) under the intensity is demodulated.
The degree of first demodulated signal indication carrier wave frequency and chamber off resonance (off resonance) in this example, and
And be used as feedback to help the pattern by the carrier frequency of laser of frequency modulation beam 22 and chamber to be locked to each other.There is spy in intracavitary
Determine the ripple formation standing wave pattern (pattern) of frequency；These specific frequencies are corresponding with the pattern of chamber.With except these specific frequencies
The ripple of frequency outside rate does not form standing wave；Such ripple and chamber off resonance.For the chamber with some chamber patterns, spectral device
The carrier frequency of laser of frequency modulation beam and the degree of chamber pattern off resonance are determined using the first frequency, demodulation frequency.Then, carrier frequency
It can be adjusted accordingly, until it is corresponding with the pattern of chamber, i.e. until it and chamber resonance, to cause the laser beam shape of intracavitary
Into standing wave pattern.In other examples, as will be described below, chamber pattern itself can for example by change the length of chamber and by
Adjustment, until the pattern of chamber is corresponding with the carrier frequency of laser of frequency modulation beam.
In the figure 2 example, the first demodulated signal is transmitted to PID (proportional-integral-differential) controls via electrical connection 82
Device 80.PID controller 80 is adjusted via electricity according to the difference of the first demodulated signal and the expectation carrier frequency of laser of frequency modulation beam 22
The electric signal that connection 84 is provided to tuner 10.Based on the input signal received by tuner 10 from PID controller 80,
The tuning provided to laser diode 6 is adjusted so that the pattern changed into the carrier frequency of laser of frequency modulation beam 22 with chamber 36
Corresponding frequency.
In other examples, the signal provided by PID controller can be used to the mode locking of chamber to laser of frequency modulation
The carrier frequency of beam.This can be by the way that the signal from PID controller to be supplied to the device (example of the length that can change chamber
Such as, PZT (piezoelectric transducer) driving or MEMS (MEMS) device) rather than that PID controller is connected into tuner 10 is complete
Into to adjust cavity length until the pattern of chamber is corresponding with the carrier frequency of laser of frequency modulation beam.For example, being used as above-described piezoelectricity
The replacement of transducer 64, can use the such device for being connected to PID controller.Herein by the carrier frequency of laser of frequency modulation beam
Rate is locked to all examples described under the background of the pattern of chamber and various features and option is also equally applicable to the mould of its lumen
Formula is locked into the other examples of the carrier frequency of laser of frequency modulation beam；Such example should be considered as disclosed herein.
The pattern of the carrier frequency of laser of frequency modulation beam 22 and chamber 36 is locked to each other can be by stablizing laser of frequency modulation beam 22
Line width aid in.This for example can be minimized and/or be passed through by the current noise for the electric current for making to be fed to laser diode 6
Mechanical noise is set to minimize or reduce the temperature fluctuation of spectral device 2 to complete.In this example, spectral device can be used to
The frequency of stable laser of frequency modulation beam 22, without mechanically or other manner shakes laser beam or chamber, for instance, it is not necessary to make
The wavelength of laser beam is relative to chamber resonating movement.For example, PZT (piezoelectric transducer) 64 can be from spectral device (for example, with nano level
Precision defines the spectral device of cavity length) in omit.In other examples, spectral device can be with laser beam and/or chamber
Shake is used in combination.
In analyte in the example of vapor, the carrier frequency of laser beam and/or the pattern of chamber can be locked into example
Such as 1392 nanometers or 1371 nanometers of wavelength.In other examples, the carrier frequency of laser beam and/or the pattern of chamber can be locked
Surely any radiation transistion of analyte is arrived.In this example, term " radiation transistion " refer to for example can with the atom of analyte or
Atom or molecular transition that electronics, core, vibration and/or the change of roton state of molecule are associated.
In this example, the carrier frequency of laser of frequency modulation beam and the pattern of chamber are in the amount with the analyte in indicating mixture
Substantially the same time time for being generated of output be locked to each other.In this example, term " substantially the same " refers to
Output is while be generated, and the carrier frequency of laser of frequency modulation beam and the pattern of chamber are locked to each other, or at least so that the locking with
The generation of the output of the amount of analyte in indicating mixture is least partially overlapped.In other examples, the load of laser of frequency modulation beam
Wave frequency rate can each other be locked from the pattern of chamber in the different time of the output with the amount of the analyte in generation indicating mixture
It is fixed.
The example of the phase-sensitive detection for the spectral device for using Fig. 2 will now be described.
In laser of frequency modulation beam 22 in modulating frequency ωmUnder be frequency-modulated in the case of, carry out the reference of voltage controlled oscillator 4
Signal VrefAnd output signal Vout(for example, the signal obtained by the first photoelectric detector or the second photoelectric detector 46,76)
Be fed into phase sensitive detector (such as, above-described first phase sensitive detector or the second phase sensitive detector 50,76) in.Originally showing
In example, reference signal VrefWith output signal VoutWith following form：
Vref(t)=sin (ωmt)
Vout(t)=V0sin(Ωt+φ)
Wherein V0Represent output signal VoutAmplitude, Ω is the frequency of output signal, and φ is relative phase, and Ω t+
φ is the instantaneous phase of output signal.
Reference signal is multiplied together by phase sensitive detector with output signal, so as to obtain signals below：
Informedness can be had more (informatively) is represented as the formula：
Wherein Ω is set equal to ωm。
The result of the phase-sensitive detection performed by phase sensitive detector is by producing the direct current (DC) under frequency interested
Export and filter out any component of signal not under desired frequency and only extract the frequency component interested.Cause
This, it is used with reference to letter in order to be demodulated under modulating frequency to the strength signal obtained by the second photoelectric detector 76
Number form be Vref=sin (ωmt).For under the harmonic wave of higher order (for example, under any n times of given modulating frequency)
Strength signal is demodulated, the form of used reference signal is Vref=sin (n ωmt).Therefore, in order in twice of tune
The strength signal obtained by the first photoelectric detector 46 is demodulated under frequency processed, the form of used reference signal is
Vref=sin (2 ωmt).In order in any specific frequencies omegaPUnder strength signal is demodulated, used reference signal
Form is Vref=sin (n ωmt)。
In this example, the second harmonic, (namely in 2 ωmFrequency under the Beat Signal interested that vibrates) indicate it is mixed
The amount of analyte in compound.For example, linear for what is given, 2f signals depend on the second dervative of transmission feature.This depends on
In the shape of transmission feature, for example, the width of transmission feature.In this example, transmission feature be the analyte in mixture to
Spectral signature is determined, for example, the radiation transistion of analyte.In this example, the shape of transmission feature depends on the fineness of chamber, the essence
Fineness is depended on because mixture absorbs the loss of the laser of frequency modulation beam caused.For very high-frequency modulation, for example, shape
Absorption Line can be depended in itself, and be accordingly dependent on both amplitudes and width of transmission feature.In other examples, modulation
The other harmonic waves or other frequencies of frequency can provide the information of the amount on the analyte in mixture.
By Vref=sin (2 ωmT) reference signal by phase sensitive detector and with Vout=V0sin(2ωmT) shape
The input signal of formula transmits generation product signal V togetherout(t)Vref(t)=V0/2[1–cos(4ωmt)].In this example, this multiplies
Product signal is sent to low pass filter, to remove high frequency (4 ωm) item, as the skilled person will appreciate.Therefore, this
Extract the DC component (V of the mixed signal0/2).In this example, the DC component extracted corresponds to the second demodulation letter
Number.
Second demodulated signal can be used to generate the output of the amount of the analyte in indicating mixture.In this example,
Extracted DC component corresponding with the second demodulated signal can be sent to dc amplifier, to amplify extracted direct current
The signal of component, so as to the output of the amount that generates the analyte in indicating mixture.In this example, then it will can be exported
The signal of amplification sends other electronic building bricks to, for example, sending front console 56 shown in Fig. 2 to and/or such as industry should
With some of other controls or data recording equipment.
In examples described above, the direct current signal of the amplification exported and the amplitude of second harmonic quadrature component into
Ratio.Therefore, produced output is to represent 2 ωmThe D. C. value of a single point on signal curve.
In this example, the first demodulated signal is similarly obtained with the second demodulated signal, but is to utilize form to be Vref=
sin(ωmT) or for any specific frequency ωpUnder be demodulated into Vref=sin (ωpT) reference signal uses the second phase sensitivity
Detector 76 and obtain.
The example illustration of the operation principle of chamber 134 is schematically shown in figure 3.The example chamber 134 is Fabry-Perot
Sieve etalon.In the other examples being described in more detail below, micro-resonator (such as, " Whispering-gallery-mode
(whispering-gallery-mode) " micro-resonator or micro-ring resonator) replace linear cavity (such as Fabry-Perot standard
Tool) used, or micro-resonator and linear cavity are used.In the other examples being described in more detail below, it can use
Multiple micro-resonators.As it will appreciated by a person of ordinary skill, in other examples, different types of chamber can be used for spectrum
In device.
In the example of fig. 3, the first mirror and the second mirror 136,138 reflect a part for incident electric fields, and through incident
Another part of electric field.Electric field at each point outside chamber 134 is marked as E in figure 31To E9.Used in the electric field of intracavitary
Reference 140 is indicated.
Influence of the chamber 134 to output intensity can be by considering the interference between the projecting beam with the different cavity life-span
To determine.In-field enters Fig. 3 example chamber 134 with the incidence angle of non-zero, with show to incide the first mirror and the second mirror 136,
The reflection of electric field on 138 and transmission principle.
In the example for the chamber 134 with being used together according to the spectrographic technique of embodiment, electric field is entered with zero incidence angle
Chamber 134 is mapped to, and absorbefacient analyte is placed in chamber 134.In this example, total transmitted field is given by infinite sum
Go out：
E1=E0ei(kx-ωt)
F2=rE1
…=…
The formula is presented in compacter form：
Wherein r and t are the range coefficient of reflection and transmission respectively, and the relation of r and t and reflectivity and transmissivity is r2=R
And t2=T, Δ φ are the overall phase shifts in the single of chamber is passed through, and δaIt is the presence of analyte on cavity length L and draws
The signal amplitude decay risen.
Overall phase shift Δ φ includes two phase terms for depending on frequency.First is transverse mode occurrence, second be by
Phase shift φ caused by the presence of analytea.Transmitted field ΕTDivided by in-field E1Obtain the transmission coefficient Τ of the laser beam of transit chamber
The new formula of (ω)：
Wherein α=δa/2L。
Total reflectance R (ω) can be obtained using identical method, that is to say, that by be 2 to numbering, 4,6,
8th ..., 2n mirror field sums to obtain：
Wherein α is the absorption coefficient of analyte, and LIIt is interaction length, wherein LIFor twice of the length L of chamber, and
And α=δa/2L。
Attenuation function δaIt is modeled as frequency (ν=ω/2 π) depending on laser, total pressure (PT) and temperature (T) Lip river logical sequence
Hereby function (Lorentzian).Expand constant (Γ) and line strength (S) can be from HITRAN databases (by Harvard-
" high-resolution transmission molecule absorption " database of Smithsonian astrophysics research center management) obtain, δaGiven by following formula
Go out：
Symbol in above-mentioned equation is defined in the following table, and these symbols have been translated into being used to work under Hz units
Appropriate unit.
Attenuation function δa(v) with dispersion function φa(v) relation between is provided by Kramers-Kronig relations：
Wherein n (ν) is refractive index, and α (v)=δa(v)/2L and wherein n (ν) and φa(v) there is following relation：
In this example, for illustrative purposes, there is chamber 134 radius of curvature to be 250 millimeters (mm) and a diameter of
12.7mm the first mirror and the second mirror 42,44.It is 2 and in the case that length is 0.25 meter (m) in refractive index, these give tool
There is the Free Spectral Range FSR for being defined as following formula of 600 megahertzs (MHz)：
Wherein c is the light velocity, and n is the refractive index of the medium of intracavitary, and L is the length of chamber.Corresponding bandwidth is FSR/F, its
Middle F is fineness, and the fineness can be considered as the measurement of the resolution capability of the optical resonator to such as chamber etc.In this example
In, the fineness F of the reflectivity limitation of chamber is 10,000.Therefore, bandwidth or full width at half maximum (FWHM) are 60kHz.In order to by laser beam
It is coupled in the example chamber, laser linewidth should be reduced to tens of kHz magnitude.This can for example by temperature, electric current and
The combination of mechanical stabilization is realized.
Provided for the resonator of storage energy or the ability of chamber by its quality factor q.This is stored in resonator
2 π times of the ratio between the energy that dissipates of energy and each cycle of oscillation：
Wherein voIt is resonant frequency
The electric field that intracavitary is damaged at preset time is given by：
E (t)=E0cos(ω0t)e-γt
To cause energy and e-γtIt is proportional, and power attenuation and γ e-γtIt is proportional.It is assumed that Fu of bilateral damped expoential
In leaf transformation be the Lorenz function for being equal to 2 γ with full width at half maximum (FWHM) (FWHM), substitute U in Q definitionstoredAnd power
Loss is provided：
Wherein δ ν are half-power bandwidths, i.e., its power ratio is in resonant frequency v0Under power a medium-sized bandwidth.
Thus obtain, Q factor is directly proportional by the fineness F of following formula and chamber：
Have 10 corresponding to 0.99969 specular reflectivity, 0.25m cavity length and 1.4 μm of resonant frequency,
Under the reflectivity restrictive condition of 000 fineness, Exemplary linear fineness of cavity will produce 3.6 × 109Quality factor.For machinery
Chamber, this is high quality factor, but can be exceeded by using the mirror or micro-resonator of ultra-high reflectivity.Micro-resonator
With can than some mirrors being incorporated in the mirror of currently available highest reflectivity two or more high orders of magnitude of linear cavity
Q factor.
Fig. 3 example chamber 134 is gone to, by the net transmission being given by：
Substitute into the equation for representing frequency modulation strength signal：
Draw the enhanced absorption spectrum signal of chamber of frequency modulation.Subsequent algebraic manipulation provides second harmonic orthogonal signalling
(sin(2ωm) component) and form：
Therefore, under given frequency, second harmonic orthogonal signalling and β, absorptivity, the product of fineness and cavity length are into just
Than wherein β and modulating frequency ωmIt is inversely proportional.This can be represented as the product of absorptivity and the ratio between modulating frequency and chamber line width,
Its lumen line width is equal to Free Spectral Range divided by fineness.
The signal depends highly on analyte concentration.In the case of direct frequency modulated-amplitude modulation(PAM), can from
Under find out in the model that provides：
The signal with frequency v0+vmUnder frequency dispersion φ1Directly it is directly proportional.
The second method for determining the enhanced 2f signals of chamber is using interaction length of equal valueThis leads to
The factor of 2F/ π~6300 is crossed to amplify " the Cavity-enhanced of the intensity of 2f signals, such as Gianfrani L et al.
absorption spectroscopy of molecular oxygen”(J.Opt.Soc.Am.b,16(12):2247-2254,
1999) as described in, the document is incorporated herein by reference.
The sensitivity of the light absorbs of detection molecules component can be carried by strengthening absorption signal and/or reduction ambient noise
Height, ideally brings up to basic quantum limit.When intrinsic uncertainty only associated with exciting (is referred to as signal
In " shot noise (shot noise) ") when obscuring absorption events, then realize highest detection sensitivity.This type
Noise be due to during detection scheme at each point produce electronics and photon discrete nature.This statistical property is
Random fluctuation during being in the process that material-photon interacts due to detector in the generation of free electron (is referred to as
" photoelectric current ") and random thermionic emission (being referred to as " dark current ").Such statistical fluctuation is inherently Poisson distribution.
In high light limitation (such as being exactly such for absorbing application), only contribution of the photon to shot noise will need to be considered.
Beer-Lambert laws think, by any inquiry (interrogating) light of length L analyte sample all will with because
Sub- eαLDecay.The decay of input signal originates from quantum mechanics, and is then due under incoming frequency for Molecular Spectroscopy
Activate (driven) dipole moment of driving and produce, so as to cause the dipole with initial fields destructive interference under the identical frequency
Radiation.
Direct absorption under given frequency is referred to as homodyne detection, and has what is provided by its shot noise limit
Peak response：
Wherein e, B, η and P0Respectively electron charge, detection bandwidth, photodetector responsivity and incident power.
The generally detection of direct absorption spectrometry is in 10-2–10-3Absorbance in scope.The shortcoming of this simple technique is it
Sensitivity be often subject in signal low-frequency noise limitation.In one example, the low frequency contribution to background signal can be
The combination of laser intensity noise, mechanical instability and other outside fluctuations.Because the power spectrum of the noise is relative to frequency
Inverse relation, the noise can be referred to as 1/f (or flicker) noise.The contribution of high 1/f noise can be by switch to ignoring
Low frequency contribution and focus on upper frequency detection (such as, frequency of use modulation spectrometry as described above is detected
Difference frequency) detection method evade.
For direct frequency modulated, the corresponding minimum detectable uptake in example is given by：
For small modulation index, this value can be more than the value provided above by shot noise limit.However, due to keeping away
Exempted from the big contribution of low-frequency noise, this can along with signal to noise ratio increase.
In this example, sensitivity can be improved via the use of optics cavity, as discussed above.When chamber enhancement effect
When being only applicable to the signal, the sensitivity of frequency modulated spectroscopy will be generally enhanced F times of chamber enhancer pi/2.Therefore, it is used for
The shot noise limit of warbled cavity-enhanced absorption spectrometry is given by：
However, it will be understood by those skilled in the art that, in other examples, spectral device can not include chamber.For example,
The optical link (for example using Herriott ponds) of folding can be used to increase optical path length.In this example, according to the side of example
Method can be used to the Carrier frequency lock by laser of frequency modulation beam to expected frequency, rather than be locked to the pattern of chamber.For example, should
Expected frequency can correspond to the radiation transistion of analyte.
In the other examples according to the spectrographic technique of embodiment, so-called " zero reading (zero-reading) " can be by
For calibration purpose.Zero reading represents the absorption of the laser beam produced due to the component in mixture in addition to analyte.
In this example, zero reading can be performed before or after the spectrographic technique of the amount for determining the analyte in mixture.
For example, by subtracting zero reading from the output generated based on the second demodulated signal, the contribution of analyte itself can be extracted,
Exclude the contribution of other absorbent components of mixture.
In this example, zero reading measurement result by by the Carrier frequency lock of laser of frequency modulation beam to when laser of frequency modulation beam with
When mixture interacts, laser of frequency modulation beam there is no the frequency of analyte absorption to obtain.In this example, term
" there is no (substantially none) " refer to analyte to the absorption of laser of frequency modulation beam relative to mixture its
Absorption of its component to laser of frequency modulation beam is in inessential or insignificant level.Indicate the frequency modulation with the carrier frequency
Second strength signal of the interaction between laser beam and mixture is demodulated, to obtain the 3rd demodulated signal.Second intensity
Signal can be demodulated under the multiple frequency of the modulating frequency, and the multiple can be the multiple of accurate (exact) or integer
(non-exact) or the multiple of non-integer of (for example, under doubled frequency of the modulating frequency) or non-precision.For example, logical
The method for crossing using the generation above with reference to the first demodulated signal and the second demodulated signal to describe, the 3rd demodulated signal is used to
Generation indicates the output of the amount for the laser of frequency modulation beam that one or more components in mixture in addition to analyte absorb.
In this example, reading measurement result be by by the Carrier frequency lock of laser of frequency modulation beam in analysis interested
Outside the spectral signature of thing, in the about low 7-10 order of magnitude of wherein line strength S with a reference value is provided region in chamber pattern
On obtain, wherein such as spectral signature can be radiation transistion.The tunability of typical laser diode is about
0.1-0.2 nanometers/Kelvin (Kelvin), the therefore near zone of (for example, in several nanometers of spectral signature) low absorption
In the presence of being desired.This keeps off resonance (detuning) temperature close to operating temperature, thus reduces zero reading and returns to this
Time between spectral signature.
The off resonance of the approximate size of carrier frequency, which can also be used, to be placed between laser of frequency modulation beam and the chamber for accommodating analyte
Etalon realize.In this example, compared with temperature off resonance, the rotation of plane Fabry-Perot etalon allows to transmission
Maximum is carried out faster and controlled wavelength is adjusted.
The use that multiple frequence rate is modulated and higher hamonic wave is detected can be combined, with the dynamic range of expanding unit.Extension
There is the benefit relevant with the amount of the information on becoming addressable overall line style to two-tone modulation (or higher).In example
In, carrier signal is modulated with the frequency of a certain scope and produces complicated pseudo-random signal.In this example, pseudorandom modulation
The carrier frequency that the use of signal corresponds to the modulating frequency of a certain scope simultaneously to laser of frequency modulation beam is modulated.By making
With digital electron device, this can provide the higher difference between the output on the measurement result to different analyte concentrations
Degree.
In the exemplary spectroscopy device according to embodiment, voltage of the photoelectric detector measurement dependent on frequency：
V (ω)=V (r (t))=V (ωc+βsin(ωmt))
Wherein r (t)=ωc+βsin(ωmT) be system receptance function.
Signal V (ω) can also be written as taylor series expansion：
By using phase sensitive detector, any DC all will be by capacitor block, and phase-sensitive detection can be used to examine
Survey nth harmonic.Shown as the V (ω) of taylor series expansion expression formula for determining given spectral signature in detail
The current potential of line style.In this example, first reproductive quality of DC (0f) offers to spectral signature amplitude at the carrier frequencies.
Estimation of the 1f offers to the derivative of feature at the carrier frequencies, and 2f two provided on feature at the carrier frequencies
The information of order derivative and the information so as to provide the curvature on this feature.Under low modulating frequency, this will be given for
The information of the structure of transmission signal, and therefore provide the information of any change on fineness of cavity.In higher modulation frequency
Under rate, and under FSR a certain multiple, this provides the possibility for the structure for allowing spread spectrum to determine molecule absorption feature.
For example, compared with the 2f signals obtained under relatively low modulating frequency, the 2f signals will be given for wherein vm=FSR three moulds
The more information of the feature curvature of transmission.
If phase-sensitive detection is in the multistage lower execution from 0f to nf, (wherein n is integer and for example can examined by electronics
The limitation of survey ability), then there is the possibility of the form of the function of prediction spectral signature.The accuracy of estimation is by with n increase
Improve, but will also be limited by the detection sensitivity under high-order harmonic wave, because modulation depth β has value
Combining the data acquisition for the spread spectrum that the modulation of multiple frequence rate and higher hamonic wave are detected can also obtain on all
Such as the more sensitive information of the change of the other parameters of temperature and pressure etc.These technologies, which can also be provided, obtains zero calibration
More efficient method.
Spread spectrum increases the bandwidth of the carrier frequency of laser of frequency modulation beam.In this example, this, which is provided, is included on inhaling
The strength signal detected of the more information of feature is received, and thus provides more detailed signal analysis method.According to showing
The spread spectrum of example is included under multiple modulating frequencies to carry out frequency modulation(PFM) to generate laser of frequency modulation beam to laser beam.Can be such as
Spread spectrum is enabled by using pseudo-random noise generator, to generate laser of frequency modulation beam.For example, this can be combined to laser of frequency modulation
The phase-shift keying (PSK) of the carrier frequency of beam is completed.This is the example of " frequency hopping ", in frequency hopping, and the carrier frequency of laser of frequency modulation beam makes
Switched with pseudo-random sequence between multiple different channels.In this example, this is equivalent to use more complicated modulation function M (t)
To replace sinusoidal modulation function；Such function can be represented by such as finite Fourier summation.
When using the spread spectrum according to example, the increase of the complexity of modulated signal is provided when demodulating strength signal
More more options.In one example, it is demodulated under each modulating frequency of the strength signal in the plurality of modulating frequency.At it
In its example, strength signal can be demodulated under one or more of the other frequency in addition to the plurality of modulating frequency.Such as
The frequency range that the carrier frequency of fruit laser beam is modulated in it has the magnitude (example of the width of the spectral signature of analyte
Such as, with chamber pattern or the magnitude of the width of the radiation transistion of analyte), then to strength signal in the frequency range
Demodulation provides the derivative of the spectral signature of analyte at multiple frequencies.To the strength signal of demodulation in a certain frequency range
Subsequent integration can be used to predict chamber pattern shape, for example, as frequency function chamber resonance shape.In example
In, compared with the demodulation under many order harmonicses in single modulating frequency, this provides more information and by the shadow of ambient noise
Sound is smaller, because the information is obtained at same order of modulation.
In this example, the non-linear property of chamber resonance will cause the generation of high-order harmonic wave under given modulating frequency.Cause
This, the example of spectrographic technique include producing by being demodulated strength signal under one or more of the other frequency one or
A number of other demodulated signals.For example, for sine input, the information on high-order harmonic wave can be by under these high order of frequency
The Fourier coefficient of each high order component for strength signal being demodulated and being obtained in high order component is obtained.In example
In, one or more of the other frequency is the integral multiple of modulating frequency, but they can not be modulation frequency in other examples
The integral multiple of rate.For example, in the example that laser beam is modulated by multiple modulating frequencies, one or more of the other frequency can be
Two or more modulating frequencies and frequency or difference frequency (difference frequency) in the plurality of modulating frequency.In this example, this
Or the modulating frequency of a number of other frequencies each more than twice.However, in other examples, one or more of the other frequency can
With less than modulating frequency.
In some cases, in mixture analyte saturation may restricted root according to the effective of the spectrographic technique of embodiment
Property.In this example, for example, in the case that analyte concentration in the mixture is relatively high, there are following one or more carrier waves
Frequency：For one or more carrier frequencies, due to analyte saturation, the laser of frequency modulation beam that ratio can be neglected passes through mixing
Thing.Therefore, for the one or more carrier frequency, the strength signal obtained afterwards in laser of frequency modulation beam is by mixture can
To be small or insignificant.In this example, this can be solved by the way that laser link is deviateed into the center of absorption signal, example
Such as, using one or more in electric current and thermal tuning, relatively strong transmission is observed until relative, and then use root
The amount of analyte is measured according to the spectrographic technique of example.Taken turns for example, laser frequency can be left to be placed in tuned with absorbing
The immediate chamber pattern in center of wide (profile), and laser frequency can alternatively be coupled to and occur the zero of saturation
In neighbouring pattern or other patterns outside signal bandwidth.Alternatively or additionally, spectrographic technique can be included chamber
Mode locking is to the pattern left in the frequency of the chamber pattern for the center for absorbing profile.
In one example, including the resonator with big Free Spectral Range (such as micro-resonator), with original
The spectral device of the resonator of son or the resonance in the afterbody of molecule line style can be selected to reduce saturation effect.Laser of frequency modulation
The saturated level of the field of beam can be used to detect different analyte concentrations.If for example, the disappearance produced with micro-resonator
Field is strong (intense), then it will be particularly suited for detecting high analyte concentration, because the saturation of evanescent field is less
It is possible.Alternatively or additionally, saturation effect can be reduced by using multiple lasing light emitters with different carrier frequencies
Should, these lasing light emitters can be used together to detect different analytes from the scanning chamber with wide scope specular reflectivity.
The hollow cavity of the mixture in use is accommodated in above with reference to the chamber of Fig. 2 and Fig. 3 devices described.However,
In other arrangements, the mixture not being contained in use still increases letter still through the active path length of increase laser beam
Number the chamber of intensity can be used.For example, it is typically solid but differ be set to solid so-called micro-resonator can
To be used in a device, to increase the intensity and the thus amount of the analyte in increase indicating mixture of laser of frequency modulation beam
The intensity of output.For example, the in-field from laser of frequency modulation beam can be coupled into micro-resonator by using such as evanescent field
In increase the intensity of laser of frequency modulation beam.In this example, laser of frequency modulation beam undergoes constructive interference in micro-resonator, thus increases
Its intensity.In this example, incided in laser of frequency modulation beam between micro-resonator and external environment condition with different refractivity
Evanescent field is produced in the case of borderline, and the evanescent field is in the external expansion of micro-resonator.In such an example, mixture
Can be close enough with evanescent field, to cause evanescent field to be interacted with mixture.For example, mixture can be adjacent with micro-resonator
Closely (for example, being contacted with micro-resonator).The amount of analyte in mixture can influence the laser of frequency modulation beam in micro-resonator to exist
The angle of the total internal reflection of boundary between micro-resonator and external environment condition, this may for example influence system via evanescent field
In loss.Then, laser of frequency modulation beam can be coupled to outside micro-resonator, and is detected using photoelectric detector, and
And the output of the amount to obtain the analyte in indicating mixture is demodulated, as described below.In this example, it can pass through
Isolator optimize sensitivity using micro-resonator.However, in other examples, micro-resonator can be embedded into another material
Layer in, the layer can be thin layer.
In other examples, two or more parallel micro-resonators with the different degrees of coupling can be used to
The sensitivity of different stage.Such example is schematically shown in Fig. 4, three micro-resonators have been used in this example.
In the example of fig. 4, being provided in container 142 includes the mixture (not shown) of analyte.Lasing light emitter 144 generates laser of frequency modulation
Beam 146, the laser of frequency modulation beam 146 is divided into further (further) first laser of frequency modulation beam, the second frequency modulation by beam splitter 148
Laser beam and the 3rd laser of frequency modulation beam 150,150', 150 ".Further first laser of frequency modulation beam 150 incides first micro- resonance
On device 152, and it is coupled to via input coupler 154 in the first micro-resonator 152.Output coupler 156 will be further
A part 158 for first laser of frequency modulation beam 150 is coupled to outside the first micro-resonator 152.Second laser of frequency modulation beam and the 3rd is adjusted
In frequency laser beam 150', 150 " being respectively coupled to the second micro-resonator and the 3rd micro-resonator 152', 152 ".Second micro- resonance
The component identical accompanying drawing similar with the corresponding component of the first micro-resonator 152 of device and the 3rd micro-resonator 152', 152 "
Identify to represent, but single dash is carried for the second micro-resonator 152', and " carried for the 3rd micro-resonator 152
Parallel dash.Further first laser of frequency modulation beam, the second laser of frequency modulation beam and the 3rd laser of frequency modulation beam 150,150', 150 "
It is micro- that the first micro-resonator, the second micro-resonator and the 3rd are left in Part I, Part II and Part III 158,158', 158 "
Resonator 152,152', 152 ", and incide the first photoelectric detector, the second photoelectric detector and the 3rd photoelectric detector
160th, on 160', 160 ".Photoelectric detector 160,160', 160 " by Part I, Part II and Part III 158,158',
158 " it is converted into indicating the strength signal of their relative intensity, and therefore these strength signals are indicated in first micro- resonance
The amount of the analyte of the relative position of device, the second micro-resonator and the 3rd micro-resonator 152,152', 152 ".
In this example, while realizing that multiple micro-resonators allow the measurement for performing wide scope, without carrying out thing to system
Reason tuning.Saturation can for example by by micro-resonator (for example, micro-ring resonator) place at different depth in a substrate come
Evade, for example, place with a distance from different from mixture is placed on, to cause at least one to provide detectable transmission signal.Showing
Example in, incide the laser of frequency modulation beam on the micro-resonator farther from mixture via the absorption of evanescent field off-energy, but
Whether saturation.By contrast, the laser of frequency modulation Shu Keneng being relatively close on the micro-resonator of mixture is incided by full
The influence of sum.
, can be similar according to the example described above to reducing saturation effect using micro-resonator in other examples
Mode come use each accommodate mixture multiple chambers.
In the other examples using waveguide, a line resonator or chamber can be used to reduce saturation effect, and this line is humorous
Shake in device or chamber each of be located at same depth in mixture, and each of be located to input coupler it is different away from
From place.
The exemplary spectroscopy dress for being used to measure the amount of the analyte in mixture according to another embodiment is shown in Fig. 5
The schematic diagram put.Using with Fig. 2 identicals reference come quoting Fig. 5 with the feature similar with reference to the feature described by Fig. 2,
But these references add 500；Corresponding description should be considered as equally applicable.
Fig. 5 spectral device 502 is similar with Fig. 2 spectral device 2, but additionally includes being used for laser of frequency modulation beam
Laser lock-on mechanism of 522 Carrier frequency lock to the spectral signature (frequency of the radiation transistion of such as analyte) of analyte
162.(in this case, water is analyte, but in general device 2,502 can be used together with other analytes, such as
It is upper described.) if such as driving current of lasing light emitter 506 or temperature are in the presence of change, the carrier frequency of laser of frequency modulation beam 522 can
Given frequency corresponding with the radiation transistion of analyte can be drifted away from, this may be mistakenly considered or be misinterpreted as to be analyte
The change of concentration.Thus, in this example, using laser lock-on mechanism (such as Fig. 5 laser lock-on mechanism) by laser of frequency modulation beam
522 Carrier frequency lock improves the accuracy of analyte concentration measurement to the radiation transistion of analyte, and reduces due to adjusting
The drift of the carrier frequency of frequency laser beam 522 and the possibility for obtaining the incorrect measurement result of analyte concentration.
In Figure 5, the laser of frequency modulation beam 522 incided on beam splitter 532 is separated.With Fig. 2 example similarly, frequency modulation
A part for laser beam 522 incides chamber, and a part for laser of frequency modulation beam 161 is directed to via mirror 570,164,166 and is used for
Laser of frequency modulation beam 522 is locked in the laser lock-on mechanism 162 of the spectral signature of analyte, rather than such as Fig. 2 embodiment
It is directed to the second phase sensitive detector like that.
Fig. 5 laser lock-on mechanism 162 includes acousto-optic modulator (AOM) (not shown), but other in other examples
Device is used.Just as known per se, AOM includes crystal of the sound wave traveling wave by it, so as to produce the refraction of sinusoidal variations
Rate.In this example, the part 568 of laser of frequency modulation beam is with sound wave traveling wave orthogonally by the crystal, and this causes laser of frequency modulation
The part 568 of beam is diffracted into some orders (order).These orders in the vectorial sum of light wave vector sum sound wave (namely
Say, the part 568 of laser of frequency modulation beam and the wave vector of sound wave traveling wave respective and) multiple be in both angle and frequency
It is upper to be separated.AOM is operated under the frequency of sound wave generally in the range of from 10MHz to 1GHz.By by the portion of laser of frequency modulation beam
It (is the unit that accommodates vapor in this example by the unit for accommodating the reference sample of analyte to be divided to 568 two diffraction orders
(but ambient humidity can also be used in analyte is the other examples of water)) obtain for the stabilized error of laser
Signal.In this example, the reference sample of analyte be for the measured mixture of the amount of its analyte or including the mixture,
For example, in the case where mixture is environment mixture.In other examples, the reference sample of analyte is separated with mixture.
The reference sample of analyte can include the component in addition to analyte, and the reference sample itself can be mixture.
Come using photodiode 168 (but can alternatively or additionally use quadrant photodetector or balanced detector)
Obtain the difference of the absorption spectrum between the order of diffraction.This includes the Absorption Characteristics for obtaining two frequency separations, the two frequencies
The Absorption Characteristics of rate separation produce the error signal of " scattered shape (dispersion shaped) " when being subtracted from one another.Pass through
Using the 0th diffraction order and the first diffraction order, zero point is placed exactly at the half of modulating frequency.For example, existing in AOM
In the case of under the conditions of Raman-Nath, by using the -1st and+l orders, then zero just resonance.
The error signal obtained by this way indicates that laser of frequency modulation beam is inclined relative to the frequency of the spectral signature of analyte
The degree of resonance.In the example of such as Fig. 5 example etc, the error signal is sent to the first PID via electrical connection 582
Controller 580.With Fig. 2 PID controller 80 similarly, Fig. 5 the first PID controller 580 is adjusted dependent on error signal
The electric signals of tuner 510 are supplied to via electrical connection 584, to change the tuning provided to laser diode 506, to incite somebody to action
The carrier frequency of laser of frequency modulation beam 522 changes into the frequency of the more closely spectral signature of the matching analysis thing.
(such as with reference to described by Fig. 5) obtains error signal using AOM can be to zeroth order time laser beam
Dependence of the spectroscopic methodology to the specific molecular property of analyte is removed or reduced in the case of applying additional modulating frequency.Showing
In example, (for example, as described above to the absorption light between the different diffraction order of the part 568 of laser of frequency modulation beam
The difference of spectrum) balance detection also reduces common mode (intensity) noise.
In the example of hgure 5, with Fig. 2 similarly, the first photoelectric detector 546 receives laser of frequency modulation beam 522 and led to
Cross the second mirror 544 and the second lens 540 leave a part for chamber 536, and the incident portion of laser of frequency modulation beam 522 is converted into
Indicate the strength signal of the interaction between laser of frequency modulation beam 522 and mixture.However, in Figure 5, strength signal is (at this
In example be electronic signal) via electrical connection 548 be sent to the first phase sensitive detector 550 (it is similarly operated with Fig. 2) and
Both second phase sensitive detectors 576.Fig. 5 the second phase sensitive detector 576 and Fig. 2 the second phase sensitive detector 76 similarly grasp
Make, and be configured as producing the first demodulated signal by being demodulated strength signal under modulating frequency.First demodulation
Signal is sent to the second PID controller 172 via electrical connection 170.Fig. 5 the second PID controller 172 is adjusted via electrical connection
174 electric signals provided to PZT (piezoelectric transducer) 564.As response, PZT (piezoelectric transducer) 564 connects via the machinery with the second mirror 544
Mechanical fine adjustment of 566 offers to the length of chamber 536 is provided, with based on the first demodulated signal by the length of chamber 536 be locked to with
The pattern of the chamber of the immediate frequency of carrier frequency of laser of frequency modulation beam 522.Therefore, Fig. 5 example had both been included laser of frequency modulation
The Carrier frequency lock of beam includes chamber being locked to the load with laser of frequency modulation beam again to the frequency of the radiation transistion of analyte
The pattern of the immediate frequency of wave frequency rate.
Above embodiment is appreciated that the illustrated examples of the present invention.Other embodiments of the invention are to be contemplated that
's.It should be appreciated that can be used alone relative to any feature that any one embodiment is described or with described its
Its feature is used in combination, and can also be used in combination with one or more features of any other embodiment in embodiment,
Or be used in combination with any combinations of any other embodiment in embodiment.Further, it is also possible to using being not described above
Equivalent and modification, without departing from the scope of the present invention, the scope of the present invention is limited in the appended claims.
Claims (44)
1. a kind of device for being used to measure the amount of the analyte in mixture, described device includes：
Lasing light emitter, the laser of frequency modulation beam being frequency-modulated for generating under modulating frequency；
Chamber, is arranged to receive the laser of frequency modulation beam；
Photoelectric detector, the intensity letter of the interaction between the laser of frequency modulation beam and the mixture is indicated for obtaining
Number；
First demodulator, for producing the first demodulated signal by being demodulated to the strength signal；
Frequency Locking mechanism, is arranged to using first demodulated signal come by the carrier frequency of the laser of frequency modulation beam and institute
The pattern for stating chamber is locked to each other；And
Second demodulator, for producing the second demodulated signal by being demodulated to the strength signal, and for based on
Second demodulated signal generates the output for the amount for indicating the analyte in the mixture.
2. device according to claim 1, wherein first demodulator is arranged to by under the modulating frequency
The strength signal is demodulated to produce first demodulated signal.
3. device according to claim 1 or 2, wherein second demodulator is arranged to by the modulating frequency
Multiple frequency under the strength signal is demodulated to produce second demodulated signal.
4. device according to claim 3, wherein second demodulator is arranged to by the modulating frequency
The strength signal is demodulated under doubled frequency to produce second demodulated signal.
5. the device according to any one of Claims 1-4, wherein be arranged to will be described for the Frequency Locking mechanism
The carrier frequency of laser of frequency modulation beam is adjusted to corresponding with desired chamber pattern.
6. the device according to any one of claim 1 to 5, wherein be arranged to will be described for the Frequency Locking mechanism
The mode adjustment of chamber is corresponding with the expectation carrier frequency of the laser of frequency modulation beam.
7. the device according to any one of claim 1 to 6, wherein the Frequency Locking mechanism is arranged to (i)
In the carrier frequency of the laser of frequency modulation beam and the pattern of (ii) described chamber at least one of be locked to and the analysis
The pattern of the chamber of the immediate frequency of frequency of the radiation transistion of thing.
8. the device according to any one of claim 1 to 7, wherein the Frequency Locking mechanism includes being used to change institute
State the device of the length of chamber.
9. the device according to any one of claim 1 to 8, wherein the chamber is a chamber in multiple chambers, it is described
Each chamber in multiple chambers contributes to receive the laser of frequency modulation beam.
10. the device according to any one of claim 1 to 9, wherein the chamber is provided by micro-resonator.
11. device according to claim 10, wherein the micro-resonator is provided by micro-ring resonator.
12. the device according to claim 10 or claim 11, wherein during the micro-resonator is multiple micro-resonators
A micro-resonator, each micro-resonator in the multiple micro-resonator contributes to increase the strong of the laser of frequency modulation beam
Degree.
13. the device according to any one of claim 1 to 9, wherein the chamber be used to accommodating it is in use described
Mixture.
14. device according to claim 13, wherein the chamber is provided by Fabry-Perot etalon.
15. the device according to any one of claim 1 to 14, described device is arranged such that the output indication
The concentration of the analyte in the mixture.
16. the device according to any one of claim 1 to 14, including be arranged to the load of the laser of frequency modulation beam
Wave frequency rate is locked as the laser lock-on mechanism of the frequency of the radiation transistion of the analyte.
17. device according to claim 16, wherein the laser lock-on mechanism includes acousto-optic modulator.
18. the device according to claim 16 or claim 17, wherein the laser lock-on mechanism includes the analysis
The reference sample of thing.
19. a kind of hygrometer, the hygrometer includes the device according to any one of claim 1 to 18.
20. a kind of spectrographic technique for being used to measure the amount of the analyte in mixture, methods described includes：
Generate the laser of frequency modulation beam being frequency-modulated under modulating frequency；
The laser of frequency modulation beam is delivered in chamber；
Obtain the strength signal for indicating the interaction between the laser of frequency modulation beam and the mixture；
The first demodulated signal is produced by being demodulated to the strength signal；
The carrier frequency and the pattern of the chamber of the laser of frequency modulation beam are locked to each other using first demodulated signal；
The second demodulated signal is produced by being demodulated to the strength signal；And
The output for the amount for indicating the analyte in the mixture is generated based on second demodulated signal.
21. spectrographic technique according to claim 20, wherein generation first demodulated signal is included in the tune
The strength signal is demodulated under frequency processed.
22. the spectrographic technique according to claim 20 or claim 21, wherein described produce second demodulated signal
The strength signal is demodulated under the multiple frequency for being included in the modulating frequency.
23. spectrographic technique according to claim 22, wherein generation second demodulated signal is included in the tune
The strength signal is demodulated under the doubled frequency of frequency processed.
24. the spectrographic technique according to any one of claim 20 to 23, wherein described by the laser of frequency modulation beam
Carrier frequency and the pattern of the chamber are locked to each other including the carrier frequency of the laser of frequency modulation beam is adjusted to and desired chamber
Pattern correspondence.
25. the spectrographic technique according to any one of claim 20 to 24, wherein described by the laser of frequency modulation beam
Carrier frequency and the pattern of the chamber are locked to each other including being the expectation with the laser of frequency modulation beam by the mode adjustment of the chamber
Carrier frequency correspondence.
26. the spectrographic technique according to any one of claim 20 to 25, wherein described pass the laser of frequency modulation beam
Being delivered to chamber includes the laser of frequency modulation beam being delivered in the chamber neighbouring with the mixture, and the acquisition strength signal includes
Obtain the interaction indicated in the mixture and by the laser of frequency modulation beam outside the chamber between caused evanescent field
Strength signal.
27. the spectrographic technique according to any one of claim 20 to 26, wherein described pass the laser of frequency modulation beam
The chamber that chamber includes making the laser of frequency modulation beam by accommodating the mixture is delivered to, the acquisition strength signal is including being referred to
Show the strength signal of the intensity of the laser of frequency modulation beam by the mixture.
28. the spectrographic technique according to any one of claim 20 to 27, wherein described by the laser of frequency modulation beam
Carrier frequency and the pattern of the chamber are locked to each other based on second demodulated signal is indicating described mix with described to generate
Exporting for the amount of the analyte in thing is performed at the substantially the same time.
29. the spectrographic technique according to any one of claim 20 to 28, wherein described by the laser of frequency modulation beam
The pattern of carrier frequency and the chamber is locked to each other including by the carrier frequency of (i) described laser of frequency modulation beam and (ii) described chamber
In pattern at least one of be locked to and the chamber of the immediate frequency of frequency of the radiation transistion of the analyte
Pattern.
30. the spectrographic technique according to any one of claim 20 to 29, wherein described by the laser of frequency modulation beam
The pattern of carrier frequency and the chamber is locked to each other including by the carrier frequency of (i) described laser of frequency modulation beam and (ii) described chamber
At least one in pattern is locked to in addition to the immediate frequency of the frequency of the radiation transistion of the analyte
The pattern of the chamber of frequency.
31. the spectrographic technique according to any one of claim 20 to 30, including：
By the Carrier frequency lock of the laser of frequency modulation beam to when the laser of frequency modulation beam and the mixture interact, institute
State laser of frequency modulation beam and there is no the frequency being absorbed by the analyte；
The laser of frequency modulation beam is delivered in the chamber；
Obtain the second strength signal for indicating the interaction between the laser of frequency modulation beam and the mixture；
The 3rd demodulated signal is produced by being demodulated to second strength signal；And
The one kind or many indicated in the mixture in addition to the analyte is generated based on the 3rd demodulated signal
Plant the output of the amount for the laser of frequency modulation beam that component absorbs.
32. spectrographic technique according to claim 31, wherein the 3rd demodulated signal passes through in the modulating frequency
The strength signal is demodulated under multiple frequency and produced.
33. spectrographic technique according to claim 32, wherein the 3rd demodulated signal passes through in the modulating frequency
The strength signal is demodulated under doubled frequency and produced.
34. the spectrographic technique according to any one of claim 20 to 33, wherein indicating described in the mixture
The concentration of the analyte in mixture described in the output indication of the amount of analyte.
35. the spectrographic technique according to any one of claim 20 to 34, wherein the mixture includes at least one
Gas.
36. the spectrographic technique according to any one of claim 20 to 35, wherein the analyte includes water.
37. the spectrographic technique according to any one of claim 20 to 36, wherein the analyte is included in following item
One or more：Oxygen, hydrogen fluoride or sulfur dioxide.
38. the spectrographic technique according to any one of claim 20 to 37, wherein the mixture except described point
Analysing the component outside thing includes one or more in following item：Air, methane, hydrogen, carbon dioxide or sulfur hexafluoride.
39. the spectrographic technique according to any one of claim 20 to 38, wherein the laser of frequency modulation beam is adjusted multiple
It is frequency-modulated under frequency processed, the multiple modulating frequency includes the modulating frequency.
40. the spectrographic technique according to claim 39, wherein the strength signal is every in the multiple modulating frequency
It is demodulated under individual modulating frequency.
41. the spectrographic technique according to claim 39, wherein the strength signal except the multiple modulating frequency it
It is demodulated under outer frequency.
42. the spectrographic technique according to any one of claim 39 to 41, wherein the laser of frequency modulation Shu Liyong it is pseudo- with
Machine modulated signal is frequency-modulated.
43. the spectrographic technique according to any one of claim 20 to 42, including by one or more of the other frequency
The strength signal is demodulated to produce one or more of the other demodulated signal under rate.
44. spectrographic technique according to claim 43, wherein one or more of other frequencies are each more than described
Twice of modulating frequency.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1421416.7 | 2014-12-02 | ||
| GB1421416.7A GB2536187B (en) | 2014-12-02 | 2014-12-02 | Spectroscopic apparatus for measuring an amount of an analyte in a mixture using a frequency-modulated laser beam |
| PCT/EP2015/078232 WO2016087450A2 (en) | 2014-12-02 | 2015-12-01 | Spectroscopic apparatus and method |
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| Publication Number | Publication Date |
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| CN107209113A true CN107209113A (en) | 2017-09-26 |
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| CN201580075183.6A Pending CN107209113A (en) | 2014-12-02 | 2015-12-01 | Spectral device and method |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US20170268930A1 (en) |
| EP (1) | EP3224586A2 (en) |
| JP (1) | JP2018502289A (en) |
| CN (1) | CN107209113A (en) |
| GB (1) | GB2536187B (en) |
| WO (1) | WO2016087450A2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109211799A (en) * | 2018-11-14 | 2019-01-15 | 国网黑龙江省电力有限公司电力科学研究院 | The method that 980nm wave band of laser measures concentration of SO 2 gas in sulfur hexafluoride gas |
| CN109211800A (en) * | 2018-11-14 | 2019-01-15 | 国网黑龙江省电力有限公司电力科学研究院 | Utilize the method for gas concentration lwevel in 632.8nm wave band of laser measurement sulfur hexafluoride gas |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20170356842A1 (en) * | 2016-06-09 | 2017-12-14 | Adelphi University | Real-time trace gas sensor using a multi-mode diode laser and multiple line integrated cavity enhanced absorption spectroscopy |
| JP2019051771A (en) * | 2017-09-13 | 2019-04-04 | トヨタ自動車株式会社 | Load transmission structure |
| WO2020184474A1 (en) * | 2019-03-08 | 2020-09-17 | 積水メディカル株式会社 | Analyzing device |
| US11921040B2 (en) * | 2019-09-12 | 2024-03-05 | Shimadzu Corporation | Gas absorbance spectrum measurement device frequency locking method, and gas absorbance spectrum measurement method |
| US11346773B2 (en) * | 2020-04-22 | 2022-05-31 | Kidde Technologies, Inc. | Fabry-Perot spectrometer-based smoke detector |
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| US20100315642A1 (en) * | 2007-12-05 | 2010-12-16 | Jong Hann Chow | Spectroscopic detection system and method |
| US20120113426A1 (en) * | 2010-09-09 | 2012-05-10 | Adelphi University | Method and Apparatus for Trace Gas Detection Using Integrated Wavelength Modulated Spectra Across Multiple Lines |
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| WO1992013265A1 (en) * | 1991-01-24 | 1992-08-06 | The University Of Maryland | Method and apparatus for multi-dimensional phase fluorescence lifetime imaging |
| US5196709A (en) * | 1991-05-03 | 1993-03-23 | University Of Maryland Systems | Fluorometry method and apparatus using a semiconductor laser diode as a light source |
| US5636035A (en) * | 1991-09-30 | 1997-06-03 | The Trustees Of The Stevens Institute Of Technology | Method and apparatus for dual modulation laser spectroscopy |
| US6727492B1 (en) * | 2000-01-13 | 2004-04-27 | Regents Of The University Of Colorado | Cavity ringdown spectroscopy system using differential heterodyne detection |
| US7283242B2 (en) * | 2003-04-11 | 2007-10-16 | Thornton Robert L | Optical spectroscopy apparatus and method for measurement of analyte concentrations or other such species in a specimen employing a semiconductor laser-pumped, small-cavity fiber laser |
| US7230712B2 (en) * | 2003-11-03 | 2007-06-12 | Battelle Memorial Institute | Reduction of residual amplitude modulation in frequency-modulated signals |
| US7616305B2 (en) * | 2006-11-30 | 2009-11-10 | Rutgers, The State University | Analytical methods and apparatus |
| US8429378B2 (en) * | 2010-07-06 | 2013-04-23 | Qualcomm Incorporated | System and method to manage a translation lookaside buffer |
-
2014
- 2014-12-02 GB GB1421416.7A patent/GB2536187B/en active Active
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2015
- 2015-12-01 EP EP15808127.3A patent/EP3224586A2/en not_active Withdrawn
- 2015-12-01 CN CN201580075183.6A patent/CN107209113A/en active Pending
- 2015-12-01 JP JP2017530207A patent/JP2018502289A/en active Pending
- 2015-12-01 US US15/532,247 patent/US20170268930A1/en not_active Abandoned
- 2015-12-01 WO PCT/EP2015/078232 patent/WO2016087450A2/en active Application Filing
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100315642A1 (en) * | 2007-12-05 | 2010-12-16 | Jong Hann Chow | Spectroscopic detection system and method |
| US20120113426A1 (en) * | 2010-09-09 | 2012-05-10 | Adelphi University | Method and Apparatus for Trace Gas Detection Using Integrated Wavelength Modulated Spectra Across Multiple Lines |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109211799A (en) * | 2018-11-14 | 2019-01-15 | 国网黑龙江省电力有限公司电力科学研究院 | The method that 980nm wave band of laser measures concentration of SO 2 gas in sulfur hexafluoride gas |
| CN109211800A (en) * | 2018-11-14 | 2019-01-15 | 国网黑龙江省电力有限公司电力科学研究院 | Utilize the method for gas concentration lwevel in 632.8nm wave band of laser measurement sulfur hexafluoride gas |
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| Publication number | Publication date |
|---|---|
| EP3224586A2 (en) | 2017-10-04 |
| GB201421416D0 (en) | 2015-01-14 |
| US20170268930A1 (en) | 2017-09-21 |
| GB2536187B (en) | 2017-08-30 |
| WO2016087450A3 (en) | 2016-07-28 |
| WO2016087450A2 (en) | 2016-06-09 |
| JP2018502289A (en) | 2018-01-25 |
| GB2536187A (en) | 2016-09-14 |
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